Role of the Ollo de Sapo massive felsic volcanism of NW Iberia in the Early Ordovician dynamics of northern Gondwana

Montes, Alejandro Díez; Catalán, José R. Martı́nez; Mulas, Félix Bellido

doi:10.1016/j.gr.2009.09.001

Cited by 114 publications

(94 citation statements)

References 59 publications

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“…(2) A voluminous extensionrelated late Cambrian to Early Ordovician magmatic event (ca. 490-470 Ma) is generally interpreted to be linked to the opening of the Rheic Ocean (Valverde-Vaquero and Dunning, 2000;Murphy et al, 2006;Bea et al, 2006b;Montero et al, 2007;Díez Montes et al, 2010;Talavera et al, 2013). (3) A scarcely represented volcanic event ca.…”

Section: Regional Settingmentioning

confidence: 99%

“…In the northwest Iberian Variscan realm these ages correspond to well-known magmatic events (see Introduction) related to the Cadomian arc orogeny (e.g., Fernández-Suárez et al, 2011) and the Ollo de Sapo event related to the lithospheric thinning caused by the opening of the Rheic ocean (e.g., Murphy et al, 2006;Linnemann et al, 2008). Ollo de Sapo is the regional term for a thick succession of augen gneisses and porphyroid acid volcanics of Early Ordovician age that crop out in many sections of the Variscan belt in western Europe (e.g., Díez Montes et al, 2010;Montero et al, 2007Montero et al, , 2017, and references therein). www.gsapubs.org | Volume 10 | Number 1 | LITHOSPHERE If we compare the apparent age spectrum of inherited zircons in the ECS and the POS (Fig.…”

Section: Zircon Inheritance and Zircon Saturation Temperaturesmentioning

confidence: 99%

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Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

et al. 2018

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In this study we report laser ablation-inductively coupled plasma-mass spectrometer U-Pb ages of granitoids from the so-called early granodiorites of the northwest Iberian Variscan belt. The U-Pb results attest to significant magmatic activity in Visean time (ca. 347-337 Ma) that generated a hitherto poorly constrained granitoid suite in the northwest Iberian tract of the western European Variscan belt realm. This early Carboniferous suite (ECS) is mainly composed of peraluminous cold and hot crustal granodiorites and monzogranites with minor associated mafic rocks that attest to minor involvement of mantle melting. Based on the geochronological and geochemical data, we compare the Visean granitoids with younger Variscan granitoids in northwest Iberia and, in view of the tectonothermal scenarios of the Variscan collision in northwest Iberia, propose a model for the genesis of the ECS in northwest Iberia that involves rapid melting upon fast exhumation of the thickened Gondwanan crust in the course of the protracted Variscan collision.

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Section: Regional Settingmentioning

confidence: 99%

Section: Zircon Inheritance and Zircon Saturation Temperaturesmentioning

confidence: 99%

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

et al. 2018

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“…An interesting marker is the Ollo de Sapo Fm, a porphyritic ensemble of subvolcanic, volcanic and volcaniclastic rocks underlying and partly intercalated with Early Ordovician, platform-facies sediments (Díez Montes et al 2010). Although Early Ordovician felsic volcanism occurs elsewhere in the Iberian Massif, the formation is only defined in a narrow strip, the Ollo de Sapo domain (Fig.…”

Section: Geometry and Zones Involvedmentioning

confidence: 99%

“…Each dome tapers and disappears laterally being replaced by other equally lens-shaped dome (Díez Montes et al 2010).…”

Section: Geometry and Zones Involvedmentioning

confidence: 99%

The Central Iberian arc, an orocline centered in the Iberian Massif and some implications for the Variscan belt

Catalán

2011

Int J Earth Sci (Geol Rundsch)

104

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An arcuate structure, comparable in size with the Ibero-Armorican arc, is delineated by Variscan folds and magnetic anomalies in the Central Iberian Zone of the Iberian Massif. Called the Central Iberian arc, its sense of curvature is opposite to that of the Ibero-Armorican arc, and its core is occupied by the Galicia-Trás-os-Montes Zone of NW Iberia, which includes the Rheic suture. Other zones of the Iberian Massif are bent by the arc, but the Ossa-Morena and South Portuguese zones are not involved. The arc formed during the Late Carboniferous, at final stages of thermal relaxation and collapse, and an origin related with right-lateral ductile transpression at the scale of the Variscan belt is proposed. The Central Iberian arc explains the width of the Central Iberian Zone, clarifies the position of the allochthonous terranes of NW Iberia, and opens new perspectives for correlations with the rest of the Variscan belt, in particular, with the Armorican Massif, whose central zone represents the continuation of the southwest branch of the arc detached by strike-slip tectonics.

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“…Nevertheless, the Rheic suture zone is now recognized in southern England and south of the Rhenish Massif, while south of this suture, many relicts of mafic-ultramafic complexes, MORB-type eclogites, alkalic magmas and contemporaneous crust-derived acidic magmatic rocks of Upper Cambrian-Lower Ordovician ages are found (see compilations in: Berger et von Raumer et al, 2013;Villaseca et al, 2015). Despite some disagreement about the source and geodynamic implication of such magmatism, it is generally agreed that at this period the northern Gondwana margin was under widespread extensional tectonics that locally led to the formation of slow-spreading oceanic crust, distinct from that of the Rheic Ocean (Berger et al, 2006;Bouchardon et al, 1989;Briand et al, 1991;Díez Fernández et al, 2012;Matte, 2001;Montes et al, 2010;Pin and Marini, 1993;von Raumer and Stampfli, 2008). In the Massif Central, this "oceanic" domain is often referred to as the Galicia-Brittany…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Pre-Cadomian to late-Variscan odyssey of the eastern Massif Central, France: Formation of the West European crust in a nutshell

Chelle-Michou¹

2017

Preprint

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The East Massif Central (EMC), France, is part of the internal zone of the Variscan belt where late Carboniferous crustal melting and orogenic collapse have largely obliterated the pre-to early-Variscan geological record. Nevertheless, parts of this history can be reconstructed by using in-situ U-Th-Pb-Lu-Hf isotopic data of texturally well-defined zircon grains from different lithological units. All the main rock units commonly described in the EMC are present in the area of Tournon and include meta-sedimentary and meta-igneous rocks of the Upper Gneiss Unit (UGU) and of the Lower Gneiss Unit (LGU), as well as cross-cuttingVariscan granitoid dikes and a heterogeneous granite coring the major Velay dome. Herein we demonstrate that the UGU and the LGU have markedly distinct zircon records. The results of this study are consistent with deposition of the protoliths of the paragneisses within a backarc basin that was located adjacent to the Arabian-Nubian shield and/or the Saharan Metacraton during the late Ediacaran and collected detritus from the Gondwana continent. At ~545 Ma some of these sedimentary rocks were affected by a first melting event that formed the protoliths of the LGU orthogneisses, those of which subsequently remelted at ca. 308 Ma to form the Velay granite-migmatite dome. Protoliths of the UGU result mainly from a bimodal rift-related magmatism at ~480 Ma, corresponding to melting of the Ediacaran sediments and depleted mantle. Zircon rims from the UGU additionally provide evidence for a metamorphic/migmatitic overprint during the Lower Carboniferous (~350-340 Ma).Finally, several generations of granite dikes of which inherited zircons display characteristics of both the UGU and the LGU were protractedly emplaced from ~322 Ma to ~308 Ma, the youngest of which being coeval with the formation of the Velay dome. Our data further show that the vast majority of crustal material ultimately involved in the Variscan orogeny, which forms the present-day basement in the EMC, was derived from a sedimentary mixture of ACCEPTED MANUSCRIPTA C C E P T E D M A N U S C R I P T various components from the Gondwana continent deposited in Ediacaran times, with no evidence for the involvement of an older autochthonous crust.

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Role of the Ollo de Sapo massive felsic volcanism of NW Iberia in the Early Ordovician dynamics of northern Gondwana

Cited by 114 publications

References 59 publications

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

The Central Iberian arc, an orocline centered in the Iberian Massif and some implications for the Variscan belt

Pre-Cadomian to late-Variscan odyssey of the eastern Massif Central, France: Formation of the West European crust in a nutshell

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